Embodiments of this disclosure generally relate to a communication system, and more particularly, to a low power radio frequency to digital receiver which may perform arbitrary bandpass filtering in the radio frequency (RF) domain and may down convert the filtered RF signals in a digital domain.
A radio receiver may convert signals from a radio antenna to a useable form. Design architectures for converting signals, received from an antenna, may include a low noise amplifier (LNA), down conversion mixers, voltage controller oscillator (VCO), low pass filters (LPFs), synthesizer loop, reference generator, analog-to-digital converters (ADCs) and digital signal processor (DSP) which may have a demodulator. These blocks of RF units and analog baseband and mixed signal circuits in the architecture may consume a significant portion of design efforts and implementation cost for an integrated receiver design. The use of non-digital circuits may also raise an issue of limited voltage (amplitude) headroom as the process technology advances and supply voltage decreases.
In one architecture, designed to reduce complexity and alleviate headroom issues by eliminating most RF and analog baseband circuits, input signals from the antenna may be amplified by an LNA and directly sampled by an ADC. Most of the analog signal processing may be deferred into the DSP. This architecture may introduce stringent requirements on the ADC. The sampling frequency of the ADC may be the Nyquist rate of RF carrier frequency, which may be higher than the signal bandwidth. It may result in an overhead of design complexity and power consumption of the synchronous sampling clock for the ADC. Even though the under sampling strategy may be adopted, extra noise may be folded into the baseband that may degrade the signal-to-noise ratio (SNR) of the receiver.
Therefore, it would be desirable to provide a system and method that overcomes the above problems.